Endophytic extract Zhinengcong alleviates salt stress-induced reproductive defects in Solanum lycopersicum

Salt stress severely impairs reproductive development in tomato plants, leading to reduced pollen viability, compromised pollen germination, abnormal pollen tube growth, and ultimately substantial yield losses. Zhinengcong (ZNC), a crude extract derived from the endophytic fungus Paecilomyces variotii isolated from wild sea buckthorn, has previously been reported to enhance plant resistance to abiotic stresses. Here, we demonstrate that ZNC effectively alleviates salt stress induced reproductive defects in tomato, restoring pollen viability and pollen tube growth and attenuating developmental abnormalities in reproductive tissues. Mechanistically, ZNC treatment downregulates the expression of key reactive oxygen species (ROS)-producing genes, including RBOHs, while upregulating antioxidant-related genes and enhancing the activities of corresponding antioxidant enzymes. These coordinated responses suppress excessive ROS accumulation in anthers, pollen grains, and pollen tubes under salt stress. Together, our findings reveal a protective role of the endophytic fungal extract ZNC in mitigating salt-induced reproductive inhibition and suggest its potential application for improving tomato reproduction in saline-alkaline soils.